57 mm/78.7 (2.24") SM-24-ZIF
57 mm/78.7 (2.24") ZIF-31

ZIF-31 twin mounting.

SM-24 submarine mount.

Description

Development started on this weapon in 1947 as a submarine AA weapon. A prototype of the SM-24 twin mount was built in 1948-1950. During testing on the prototype several defects were discovered and the mounting was sent back for rework. Following a redesign to correct the faults an improved version was tested from 1951-1953. This version was accepted into service in 1955 and by 1991 there were 70 mounts in the Soviet Navy.

ZIF-31 was a surface-ship version of the SM-24 mount which was designed in 1954 and accepted into service in 1955. By 1981 there were 265 ZIF-31 mounts in the Soviet Navy. There were four different versions of the mount, the main difference being that ZIF-31 and ZIF-31S had a central fire control system while the ZIF-31B and ZIF-31BS had only local control.

These weapons had significant operational problems, most of them connected to the fact that they were in open mounts, which caused problems for ships operating in the Arctic Ocean and meant that they lacked NBC protection. The guns themselves were clip fed, which lowered down their practical rate of fire. They could only be fired for 50 rounds at a time before they had to be cooled by running sea water through the barrel for 1-1.5 minutes using a special nozzle.

The barrel was of monobloc construction. The automatic mechanisms operated via the recoil forces. Both barrels were mounted on a common cradle. Ammunition was supplied in clips with each clip holding 3 rounds.